At my current job, the dress code is 'business casual'. Being in an area where there's a certain amount of physical labour involved each day, the management are quite lenient and it tends to veer more towards the 'casual' end of the spectrum. (The only real restriction is no jeans except on Fridays.) For a while, after being convinced by some friends that it would be good for my career, I tried wearing more upmarket clothes. But they kept getting ripped when they got caught on things, and dusty when I was in the storage area, not to mention stained when I spilt coffee etc. on them. It was very frustrating - ruining these fancy clothes that I'd spent so much money on. Another important factor is that I felt like a right wally dressed up to the nines when I was pushing a trolley around delivering people's mail. So once I'd ruined all those clothes, I went to the other end of the spectrum and went as cheap and casual as I could get away with. But that didn't feel right either. I felt like a bit of a slob. I felt like - if I wasn't trying at all in my appearance, then people might think I wasn't trying in my work, either. So I went for a happy medium. Proper pants in the winter, capri pants in the summer, and a range of tops which sit all over the spectrum from 'business' to 'casual-ish'.
In my new workplace, the dress code is 'business'. That's pretty daunting, and I feel especially so for someone of my size! The range of clothes available to me is pretty limited. And I limit myself further in what I prefer and what looks good on me. Here's the 'no' list:
NO skirts or dresses! Pants only for me. I used to wear skirts to work years ago. But now ... I have too much to do all day without worrying about whether my skirt is creeping half-way up my leg or if my thighs are rubbing together.
NO shirts! Or at least - no tops with a detail down the front. If the upper half has buttons etc., that's fine. But if there's any detail on the lower half, it just draws attention to my large stomach. And, lawd help me, especially not wrap tops! They just make my chest appear even smaller than it already is. Additionally, I'm not at the point yet where I can wear a top tucked in, or with a belt. ... Well, a belt is OK as long as it goes just under my bust, and the upper part poufs over.
(When I say '"I'm not at the point yet", do I mean physically or mentally? I'm not really sure of that myself!)
NO long sleeves! Or 3/4 sleeves. They have to be short or I get too hot and the feel of them on my arms is annoying. A lot of people say that girls with big arms shouldn't wear cap sleeves, but I think they're cute, so I don't care. As for sleeveless? Well, you have to be very careful or it looks too casual. If I found the right garment, and it was a very hot day, I might be able to summon up my fabulous alter-ego and give sleeveless a go...
NO white! And probably not beige or yellow either. Not because, as they say, white makes you look bigger, but because white shows up stains worse and I always worry that it's become see-through. (I do look good in most colours except yellow and light orange shades anyway.)
NO heels! I can only wear flat shoes. And only certain types. I love ballet flats, so that's OK. But I can only wear ones that are elasticated or they slip right off and/or rub badly on my heels. Mary Janes (that have a strap over the top) are fine also, but they must have a soft heel or, again, I'll get terrible blisters. Winter is OK because I can just wear ankle boots. I hate shoe shopping, as you can imagine!That's a fairly specific order, isn't it? Hm, I may have some trouble.
I'm probably being a bit premature here. I don't have any details on what the dress code really is, just a vague description of 'business'. I should probably wait until I have more information - see if there's a guide in my welcome pack, or observe what all the other women are wearing and take my cues from that. But I can't help thinking/worrying about it already, and I do like to be prepared. For fun I had a bit of a trawl through the intertubes, and here are a few outfits that I can see myself wearing:

Jessica from My Life & Style Blog
I would probably look for a jacket/cardigan with short sleeves, though.
And flats, of course.

Random pic from google.
This top has a nice ruffle detail on the bust,
but is smooth over the stomach.

Another random pic from google.
The little ruffle at the shoulder would probably
make me feel slightly less bare-armed!

Jessica from My Life & Style Blog again.
Love this black outfit with coloured layer over the top.
I have a red shrug I wear this way.

Pic from a site with tips for over 40s. Kinda demoralising. =(
This top is quite nice.
Colourful without being circusy.
It was quite hard coming up with these. It was all shirt, shirt, shirt, wrap top, shirt. A bit depressing, really. And, like I said before, I'm not really sure what I'll be able to get away with.
Tomorrow I might look for some outfits that I'd wear if size/availability were not an issue at all, for a bit of inspiration.